3GPP2 packet data standard TIA/EIA/IS835 CDMA 2000 Wireless IP Network Standard, (IS-835) and the IEEE 802.16-2005 standard herein referred to as WiMAX) communication standard, among other packet data communication systems, can specify an Active state and a Dormant (Idle) state for a wireless communication device, such as a mobile station (MS), during a packet data session. In the Active state, the MS is connected to infrastructure equipment via a dedicated RF connection. For example, in IS-835 the infrastructure provides a dedicated connection between a Base Transceiver Station (BTS) and a Packet Control Function (PCF). The PCF is connected to a Packet Data Service Node, which is connected to a packet network. A packet call is moved into the Active state when there is a burst of packet data to transmit. The packet call may transition between the Active state and the Dormant (Idle) state many times, depending on the bursty nature of the data and on the duration of the time period.
In the Dormant state, when the MS is not transmitting or receiving data, the dedicated Radio Frequency (RF) connection and the dedicated connection between the BTS and the PCF are released. The packet call transitions from the Active state to the Dormant state when there has been no data transmission for a predetermined time period. While the packet session is in the Dormant state, bearer data cannot be transmitted, and must be buffered. A network element is responsible for tracking the MS mobility, receiving packet data, and buffering it until the MS becomes active again. For example, the Packet Control Function is only useful when the mobile is Dormant. It keeps the context for the Dormant mobile and maintains a tunnel with the PDSN. When the data starts to flow from the network side, the PDSN forwards the packet to the PCF which causes the PCF to transmit a BS Service request to the MSC. The mobile is then paged and when it responds a traffic channel (TCH) and Selector are assigned to the mobile which then transitions from Dormant to Active state. In short, in order to transmit buffered data to the MS, the call must be assigned a dedicated RF connection, and a dedicated connection between the BTS and the PCF must be re-established. The delay incurred in order to re-establish a dedicated connection between the MS and the PCF (i.e. tunneling and detunneling across the A10 and A8 interfaces) has a negative impact on the quality of the data service. Moreover, during the Active state the PCF acts as nothing more than a conduit for the data between the MS and the PDSN. Thus, the PCF resources are unnecessary when the mobile is Active. A similar process occurs for WiMAX communications.
Current standards impose a high transaction cost on centralized processing elements for the time needed for Dormant (Idle) to Active transitions. The time needed has a potentially negative impact on a subscriber's perception of data service. These problems encourage configurations where the RF connection is maintained for a long period of time after transmission of a data burst, so that a subsequent data burst can immediately be transmitted. However, maintaining a connection for an unnecessarily long period of time is an inefficient use of RF resources. For example, if a channel is maintained for sixty seconds for transmission of a series of bursts of packet data, one channel can offer sixty Busy Hour Call Attempts (one channel*3600/60). If, however, the channel is maintained for only five seconds for transmission of a burst, one channel can offer 720 BHCA (1 channel*3600/5). In the latter case, Dormant to Active transitions (i.e. call attempts) will increase because the channel is maintained for a shorter period of time. In the former case, the long timeout period decreases the effective utilization of the dedicated channel, and increases the number of dedicated channels required to support the packet data service.
One prior art solution, provided in U.S. Pat. No. 6,965,588, introduces a Semi-Dormant state to address this problem. In this reference, for the Dormant state, the network element maintaining the connection to the PDSN is the PCF, and in the Semi-Dormant state, the network element maintaining the connection between to the PDSN is the Selection and Distribution Unit (SDU). In the Dormant state, the SDU is released, with the PCF maintaining the connection to the PDSN. When the MS is in the Semi-Dormant state, the network element maintaining the connection between the BS and the PDSN for the call is the SDU. When a mobile moves from the Active to the Semi-Dormant state, the traffic channel is released but the SDU stays assigned. A path exists between the SDU and the PDSN via the PCF. When the mobile is in the Semi-Dormant state, there are paths between the SDU to the PCF and the PCF to the PDSN. No traffic channel exists over the RF connection. Once the mobile transitions from the Dormant to the Active state, a traffic channel will exist from the MS to the SDU via the BTS. However, this results in the PCF always being present and utilized. The mobile is sent addresses of the serving element and the IP address of both the PCF and SDU are sent to the mobile, so that when the mobile goes Active both the SDU and PCF elements serving that mobile can be quickly identified. This solution, although effective requires a third, Semi-Dormant state to be coordinated, and still requires the PCF in the communication path while the mobile is Active, which wastes RF resources.
Therefore, there is a need for a method and apparatus for efficient transitions between operating states in a communication network, and in particular for transitioning a wireless communication device between the Dormant state and Active state by efficient connection of RF resources dependent upon whether there is bearer data to transmit.
Skilled artisans will appreciate that common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted or described in order to facilitate a less obstructed view of these various embodiments of the present invention.